Wave-current Interactions in the California Current Region: Potential
Implications for SWOT
Abstract
While waves propagating over a uniform current are simply subject to a
Doppler shift of their phase, inhomogeneous flows can modify the
wavenumber, direction, and amplitude of the waves, having the potential
to largely modulate the surface wave field. Even though the theoretical
basis for such interactions is well established, comprehensive
observations and modeling of wave–current interactions are mostly
limited to either tidal or large–scale currents and a lot remains
unknown about how waves and currents interact when both fields are
highly variable, such as near ocean fronts and eddies. In the present
work, the extent to which the surface wave field off the California
coast is modulated by the California Current System is investigated.
Optimized currents and winds from a state estimate of the California
Current System are used to force the wave model WaveWatch III in order
to quantify the relative importance of local winds and currents in
modulating the surface wave variability in this region. As satellite
altimeters evolve towards resolving finer scales, knowing the wave field
with precision may help the interpretation of sea surface height
measurements at high wavenumbers and frequencies, which has particular
relevance for the planning of the Surface Water and Ocean Topography
(SWOT) mission.